Spinel LiMn₂O₄ as Electrocatalyst toward Solid-State Zinc–Air Batteries

Abstract

Efficient oxygen reduction reaction (ORR) electrocatalysts are the key to advancement of solid-state alkaline zinc–air batteries (ZAB). We demonstrate an electrocatalyst, spinel lithium-manganese oxide LiMn2O4 (LMO) by a simple hydrothermal method. Scanning electron microscope (SEM), X-ray diffraction (XRD), and Raman spectra indicate that the as-synthesized LiMn2O4 presents nanoscale irregular-shaped particles with the well-known spinel structure. The polarization curve, chronoamperometery curve, and linear scanning voltammograms of rotating disk electrode (RDE) results reveal that the as-synthesized LiMn2O4 possesses a higher electrocatalytic activity than that of electrolytic manganese dioxide for the ORR. A solid-state zinc–air cell with LiMn2O4 as the air electrode catalyst has a long voltage plateau of discharge and a discharge capacity of 188.4 mAh at a constant discharge current density of 10 mA·cm−2. In summary, spinel LiMn2O4 in which the JT effect enables electron hoping between Mn3+ and Mn4+ can be regarded as an effective robust oxygen reduction catalyst.

Keywords

• electrocatalyst
• oxygen reduction reaction
• air electrode
• electrocatalytic activity
• solid-state zinc–air cell